On Wed, 11 May 2011, Kazuya Mio wrote: > We hit BUG_ON in ext4_ext_put_gap_in_cache() while creating a file > whose size is the max file size of extent format. Because the extent cache > length is 0 when we allocate two blocks to the file offset 2^32-2, and then > the offset 2^32-1. To fix it, we decrease the max file size to > (2^32-2)*blocksize. In this way, we would be able to allocate a block up to > the offset 2^32-2. I think there is no data loss because we can read all files > created before applying this patch. > > How to reproduce: > I'm running 2.6.39-rc6. Note that i386 architecture and 4KB blocksize cannot > reproduce this problem. > > # dd if=/dev/zero of=/mnt/mp1/file bs=<blocksize> count=1 seek=$((2**32-2)) > # sync > # dd if=/dev/zero of=/mnt/mp1/file bs=<blocksize> count=1 seek=$((2**32-1)) Hi Kazuya, Thanks for the patch, however I think that there is a better solution than lowering the max file size, which is not necessary. I would rather fix ext4_ext_put_gap_in_cache() and allow to invalidate the cache by setting the length to zero. Please see the following patch, if it works for you. Thanks! -Lukas > > Signed-off-by: Kazuya Mio <k-mio@xxxxxxxxxxxxx> > --- > fs/ext4/super.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 8553dfb..fce0249 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -2248,8 +2248,8 @@ static loff_t ext4_max_size(int blkbits, int has_huge_files) > > /* 32-bit extent-start container, ee_block */ > res = 1LL << 32; > - res <<= blkbits; > res -= 1; > + res <<= blkbits; > > /* Sanity check against vm- & vfs- imposed limits */ > if (res > upper_limit) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
